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From: Douglas Anderson <dianders@chromium.org>
To: Petr Mladek <pmladek@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: kgdb-bugreport@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	linuxppc-dev@lists.ozlabs.org,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	sparclinux@vger.kernel.org,
	"David S . Miller" <davem@davemloft.net>,
	linux-perf-users@vger.kernel.org,
	Douglas Anderson <dianders@chromium.org>
Subject: [PATCH 07/10] watchdog/buddy: Don't copy the cpumask in watchdog_next_cpu()
Date: Fri, 26 May 2023 18:41:37 -0700	[thread overview]
Message-ID: <20230526184139.7.If466f9a2b50884cbf6a1d8ad05525a2c17069407@changeid> (raw)
In-Reply-To: <20230527014153.2793931-1-dianders@chromium.org>

There's no reason to make a copy of the "watchdog_cpus" locally in
watchdog_next_cpu(). Making a copy wouldn't make things any more race
free and we're just reading the value so there's no need for a copy.

Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 kernel/watchdog_buddy.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/watchdog_buddy.c b/kernel/watchdog_buddy.c
index 3ffc5f2ede5a..2ef88722c5e7 100644
--- a/kernel/watchdog_buddy.c
+++ b/kernel/watchdog_buddy.c
@@ -10,12 +10,11 @@ static cpumask_t __read_mostly watchdog_cpus;
 
 static unsigned int watchdog_next_cpu(unsigned int cpu)
 {
-	cpumask_t cpus = watchdog_cpus;
 	unsigned int next_cpu;
 
-	next_cpu = cpumask_next(cpu, &cpus);
+	next_cpu = cpumask_next(cpu, &watchdog_cpus);
 	if (next_cpu >= nr_cpu_ids)
-		next_cpu = cpumask_first(&cpus);
+		next_cpu = cpumask_first(&watchdog_cpus);
 
 	if (next_cpu == cpu)
 		return nr_cpu_ids;
-- 
2.41.0.rc0.172.g3f132b7071-goog


WARNING: multiple messages have this Message-ID (diff)
From: Douglas Anderson <dianders@chromium.org>
To: Petr Mladek <pmladek@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: kgdb-bugreport@lists.sourceforge.net,
	linux-kernel@vger.kernel.org,
	Douglas Anderson <dianders@chromium.org>,
	linux-perf-users@vger.kernel.org,
	Nicholas Piggin <npiggin@gmail.com>,
	sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	"David S . Miller" <davem@davemloft.net>
Subject: [PATCH 07/10] watchdog/buddy: Don't copy the cpumask in watchdog_next_cpu()
Date: Fri, 26 May 2023 18:41:37 -0700	[thread overview]
Message-ID: <20230526184139.7.If466f9a2b50884cbf6a1d8ad05525a2c17069407@changeid> (raw)
In-Reply-To: <20230527014153.2793931-1-dianders@chromium.org>

There's no reason to make a copy of the "watchdog_cpus" locally in
watchdog_next_cpu(). Making a copy wouldn't make things any more race
free and we're just reading the value so there's no need for a copy.

Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 kernel/watchdog_buddy.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/watchdog_buddy.c b/kernel/watchdog_buddy.c
index 3ffc5f2ede5a..2ef88722c5e7 100644
--- a/kernel/watchdog_buddy.c
+++ b/kernel/watchdog_buddy.c
@@ -10,12 +10,11 @@ static cpumask_t __read_mostly watchdog_cpus;
 
 static unsigned int watchdog_next_cpu(unsigned int cpu)
 {
-	cpumask_t cpus = watchdog_cpus;
 	unsigned int next_cpu;
 
-	next_cpu = cpumask_next(cpu, &cpus);
+	next_cpu = cpumask_next(cpu, &watchdog_cpus);
 	if (next_cpu >= nr_cpu_ids)
-		next_cpu = cpumask_first(&cpus);
+		next_cpu = cpumask_first(&watchdog_cpus);
 
 	if (next_cpu == cpu)
 		return nr_cpu_ids;
-- 
2.41.0.rc0.172.g3f132b7071-goog


  parent reply	other threads:[~2023-05-27  1:43 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-27  1:41 [PATCH 00/10] watchdog: Cleanup / fixes after buddy series v5 reviews Douglas Anderson
2023-05-27  1:41 ` Douglas Anderson
2023-05-27  1:41 ` [PATCH 01/10] watchdog/hardlockup: Keep kernel.nmi_watchdog sysctl as 0444 if probe fails Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 14:15   ` Petr Mladek
2023-05-30 14:15     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 02/10] watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe() Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 14:38   ` Petr Mladek
2023-05-30 14:38     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 03/10] watchdog/hardlockup: Don't use raw_cpu_ptr() in watchdog_hardlockup_kick() Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 14:39   ` Petr Mladek
2023-05-30 14:39     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 04/10] watchdog/hardlockup: In watchdog_hardlockup_check() use cpumask_copy() Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 14:40   ` Petr Mladek
2023-05-30 14:40     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 05/10] watchdog/hardlockup: remove softlockup comment in touch_nmi_watchdog() Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 14:42   ` Petr Mladek
2023-05-30 14:42     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 06/10] watchdog/buddy: Cleanup how watchdog_buddy_check_hardlockup() is called Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 14:56   ` Petr Mladek
2023-05-30 14:56     ` Petr Mladek
2023-05-27  1:41 ` Douglas Anderson [this message]
2023-05-27  1:41   ` [PATCH 07/10] watchdog/buddy: Don't copy the cpumask in watchdog_next_cpu() Douglas Anderson
2023-05-30 14:57   ` Petr Mladek
2023-05-30 14:57     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 08/10] watchdog/buddy: Simplify the dependency for HARDLOCKUP_DETECTOR_PREFER_BUDDY Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 14:58   ` Petr Mladek
2023-05-30 14:58     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 09/10] watchdog/hardlockup: Move SMP barriers from common code to buddy code Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-05-30 15:00   ` Petr Mladek
2023-05-30 15:00     ` Petr Mladek
2023-05-27  1:41 ` [PATCH 10/10] watchdog/hardlockup: Rename HAVE_HARDLOCKUP_DETECTOR_NON_ARCH to ..._PERF_OR_BUDDY Douglas Anderson
2023-05-27  1:41   ` Douglas Anderson
2023-06-01 13:03   ` Petr Mladek
2023-06-01 13:03     ` Petr Mladek

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